In a plane, during a shock, a collision, or a crash, the passengers' heads are projected frontward. When the shock is significant, the passengers' heads may hit the seats in front of them, which may cause serious injuries to the passengers.
It is thus advantageous to have devices making it possible to tilt the backs of the seats frontward in case of a shock in order to reduce the impact of the passengers' heads. In this field, French Patent No. FR 2904796 and German Patent No. DE 19613506 are known, which each disclose a shock absorption device including a first element in the shape of a plate having a hole and a second element inserted into this hole, the first element including a sequence of cuts succeeding along a deformation direction and defining a sequence of bridges, extending along an extension direction transversal with respect to the deformation direction.
Such devices make it possible to absorb the energy of a shock, but they do not make it possible to tilt the seat at a significant angle. In addition, to have efficient shock absorption, it is necessary to from the devices with sequence of complicated cuts and bridges, which are costly and difficult to obtain. In addition, in those devices, it is difficult to control the resisting stress that is opposed by the device. More particularly, because the resisting stress may vary as a function of the behavior of the bridges when they are broken, that stress is difficult to establish when broken bridges form an obstacle for the second element that causes the travel thereof to vary.